Meaning & use
jack-knifing
Last updated
“jack-knifing” is a form of “jack-knife”. See that entry for the full set of meanings.
Meanings
noununcountable
The dangerous folding of a large vehicle, such as a truck, so that its parts form a sharp angle like a closing knife.
Grammar: Used as a noun, often after 'a' or 'the': a jack-knifing; the jack-knifing of the truck.
Patterns
- a jack-knifing of something
The jack-knifing of the truck blocked the whole highway for hours.
Heavy rain caused a jack-knifing on the motorway this morning.
verbintransitive
Present participle of 'jack-knife': (of a large vehicle) to fold at a sharp angle, usually in an accident.
Grammar: No object; the vehicle itself jack-knifes. Often used in progressive tenses: was jack-knifing.
Patterns
- something is jack-knifing
The truck was jack-knifing across two lanes when the police arrived.
The trailer kept jack-knifing on the icy road.
Common combinations
- cause a jack-knifing
- The sudden braking caused a jack-knifing of the trailer.
- avoid a jack-knifing
- Drivers are taught how to avoid a jack-knifing in wet conditions.
- jack-knifing accident
- A jack-knifing accident closed the southbound lane.
Word family
- jack-knife verb
- To fold at a sharp angle, as a large vehicle does.
- jack-knife noun
- A large folding knife, or the act of folding sharply.
Commonly confused: jack-knifing or jackknife?
jack-knifing vs jackknife
This is the same word without a hyphen. Both spellings are used, but 'jackknife' is more common in American English.
Practice
The truck was ____ on the icy bridge, blocking both lanes.
Choose one answer.
'Was jack-knifing' is the past progressive, describing an action in progress. 'Jack-knifed' would be simple past and would need a different sentence structure, while 'jack-knifes' is present tense and does not fit 'was'.
Make it your own
Write a sentence using “jack-knifing”, then check it and compare it with the examples above.